Defects 



PARAFFIN SECTIONS 



127 



Table 3 



DEFECTS APPEARING IN SECTIONS AFTER STAINING AND MOUNTING 



Defect 



Cause 



Remedy 



Method of Prevention 



Sections 

 distorted 



Sections appear 

 opaque or have 

 highlj' refrac- 

 tive lines out- 

 lining cells and 

 tissues 



Sections will 

 not take stain, 

 or stain 

 irregularly 



Sections con- 

 tain fine opaque 

 needles or 

 granules 



1. Blunt knife and 

 soft wax 



2. Ribbon stretched 

 when picked up on 

 hot day 



3. Tissues not properly 

 hardened before 

 embedding 



1. Clearing agent 

 evaporated before 

 mountant added 



2. Sections insuffi- 

 ciently cleared or 

 cleared in agent 

 not miscible with 

 mountant 



1. Wax not perfectly 

 removed before 

 staining 



2. Section not uniform 

 thickness 



3. Tissue "old" (has 

 been stored for a 

 long time in alcohol 

 or, worse still, fLxa- 

 tive) 



4. Fixative not suit- 

 able before staining 

 technique employed 



5. Fixative not fully 

 removed 



1. Imperfect removal 

 of mercuric fixatives 



None, though pro- 

 longed flattening on 

 warm water may 

 help 

 As (1) above 



3. None 



1. None 



2. Soak off cover. 

 Clear properly 



1. Return sections 

 through proper se- 

 quence of reagents 

 to xylene. Leave un- 

 til wax removed. 

 Restain 



2. None 



3. Return sections 

 through proper se- 

 quence of reagents 

 to water. Wash 

 overnight. If not 

 effective try a "tis- 

 sue reviver" 

 (Chapter 22, ADS 

 11) 



4. Try mordanting 

 sections in recom- 

 mended fixative 



5. Consult Chapter 

 10, ADS 11 



1. Return sections 

 through proper se- 

 quence of reagents 

 to water. Treat 30 

 min. with Lugol's 

 iodine, rinse, and 

 bleach in 5 % so- 

 dium thiosulfate. 

 Restain 



1. 



Use suitable knife 

 and embedding 

 medium 



Handle ribbons in 

 short lengths or use 

 harder wax 



Use more suitable 

 fixative or fix longer. 

 Take extra care in 

 dehydrating, clear- 

 ing, and embedding 



Obvious 



2. 



Check quality and 

 nature of clearing 

 agents and 

 mountants 



1. Change first jar of 

 xylene frequently 



2. See table 1 



3. Store all tissues 

 embedded in paraf- 

 fin blocks — never 

 liquids 



4. Obvious 



5. Treat tissues as in- 

 dicated 



1. Treat tissues as in- 

 dicated in Chapter 

 10, ADS 11 



